This invention relates to a machine for applying labels to containers such as bottles as they are conveyed past a label application station.
In a known type of labeling machine a disk or rotor is rotated about a vertical axis at a constant speed. The rotor has several pallet shafts arranged in a circle around its axis. Each shaft has a glue pallet and the pallets have surfaces for receiving a coating of glue which surfaces are segments of a circle. A mechanism is provided for oscillating the shafts about their vertical axes so that each pallet can engage a glue applicator roller in a rocking or rolling fashion and then continue in a circular path to a label stack where a label becomes adhered to the pallet. After rolling over a glue label and picking it up, the pallet continues in its circular path to a transfer drum which picks the label off of the pallet and carries it around to the station where it is pressed on the bottle that has been conveyed to the station at the moment. When there is a gap in the line of bottles being conveyed toward the label application station, it is necessary to interrupt the label pick up and transfer operations lest the machine become fouled with labels. Accordingly, means are provided to detect that a gap of one or more bottles will occur at the application station. In prior art apparatus, air pressure actuated couplings or clutches are used to operate a mechanism that restrains the pallet shaft against oscillation at an angle wherein the glue surface segment of the pallet is held away from the glue roller and label stack. After the pallet has at least passed the label stack, the oscillating motion of the pallet shaft is restored but is again interrupted if, by the time the pallet gets to a predetermined position in its orbit, there is no bottle at the label application station. Prior art mechanisms for deactivating and reactivating pallets have been structurally complicated and composed of heavy parts since they must stop pallet oscillation abruptly and restore it abruptly. The operating parts of the mechanism must move through a substantial distance at high speed so they are inclined to wear to the point where they require replacement or maintenance in a less than desirable amount of time. Moreover, prior labeling machines have the disadvantage of requiring coupling or uncoupling of the pallet shafts at a single point or within a very small angular range in the orbital path of the pallets.